By Dr. Charlene E. Reid

As gross as it sounds many animals lick their wounds. That is just a simple fact of nature. My son recently asked me why he couldn't lick the scrape on his arm after he fell, ( he's only five). To be honest I really didn't know why.

Are tissues, Band-aids, and a tube of neopsorin really substitutes for licking? Or do they run the risk of denying saliva one of its intended physiological functions?

What is Saliva?

Saliva is a fluid of mostly water which is secreted out of three pairs of salivary glands within the mou-th.These pairs are called the parotid, the submandibular and the sublingual glands. Indeed, these are the big three, responsible for every spit and every puddle of drool on one's pillow in the morning.

Now, what is the chemical composition of saliva? The stuff is mostly water (98 percent), and this portion of it is really somewhat inconsequential and no different from what comes out of the kitchen faucet.

Obviously, if saliva was only water, one might as well just have a bottle of Sunny Isles laying around at all times for all the good it would do. Indeed, it's the remaining two percent that's the key to the importance of saliva.

This deceptively small portion contains several different chemicals - mucous, electrolytes, antibacterial compounds, and enzymes - all of which play their own particular role in one's mouth.

The enzymes in particular are pretty crucial, and one of them specifically: Ptyalin (from the amylase family of enzymes) serves to break down the starches in the food we eat, beginning the crucial processes of digestion long before the food ever reaches the stomach. It would surely be missed if it was gone.

The small amount of mucous within saliva turns it into what's called an alkaline chemical, meaning that it acts to neutralize acids in the mouth.

Why is this important? Well, when the urge is felt to vomit and the brain sends signals to the mouth to rapidly increase salivation, one should be grateful, because the acid from the stomach can be quite hazardous inside the mouth, throat and teeth. Saliva, in other words, protects the mouth from vomit.

Saliva acts to lubricate food in order to allow it to slide through the oesophagus without any unnecessary discomfort.

It allows one to taste what is being placed in the mouth.

It also aids in oral hygiene by cleaning unwanted microbes and bacteria from the mouth (the fact that the salivary glands slow down production during the night is the reason for "morning breath"), and the list goes on.

As for licking wounds... saliva definitely has an antibacterial element to it (and even trace amounts of hydrogen peroxide), which does, in fact, make it a bit more effective at cleaning wounds than actual water. In this light, perhaps this is one of its intended purposes that we simply don't use often enough. I think I'll stick to modern techniques.

Saliva is not just a gift to animals, but it is an important one to humans as well, and one that is far too often taken for granted.